I've got an 07 impala LS 3.5L V6. Car has a rough idle.... RPM's drops down to 550 to 600rpm once it reaches operating temp and it has been driving in stop and go traffic like when commuting to work.

So problem is this rough and low rpm idle that drops to 550rpm once stopped at a red light but when I run the a/c the idle comes up to the normal for that car at 700rpm however this rough idle is still there. So I replaced the plugs, wires, cleaned the mass airflow sensor and throttle body thinking that's my issue, well the idle started to rocket to 900 to 1000 rpm but that's because I disconnected the battery and unhooked the sensors when I did my cleaning the computer needed to relearn it's factory idle preseting. Car drove great for a week, then idle was normal and before I knew it that rough idle came back. Guys I'm stumped....NO CHECK ENGINE LIGHTS..... maybe my exhaust ? Catconverter? Or exhaust hanger or loose bolts cause the vibrations? What gives? Maybe an early failing stage for my 02 sensors?

7 Answers

Ok after living with that issue for 2
months finally got the problem
solved. It was 2 items that were
compromised. 1st being my power
steering pump was in the beginning
phase of seizing and failing. The
pump began to create a rotational
drag on the serpentine belt due to
the resistance because the pump
was seizing. That brought down the
idle. 2nd was the bottom motor
mount was completely shot I'm
talking about there was no rubber
what so ever. Replaced the
serpentine belt, power steering pump
and the motor mount and the car
drives really smooth and quite. Car
idles at 700rpm.

It wasn't the battery, believe it or not I
wrote that problem with that car
about a year ago and solved it if you
look and read out on my 2nd
response. Fortunately, I am now the
proud new owner of a new 2015
impala.

I determined that by 2 reasons. Power steering was
getting a whining like noise much like it does when the
fluid level is low but that wasn't the case the pulley was
actually in the beginning phase of seizing up creating the
whining noise and 2nd the bottom motor mount was shot
completely deterioted so the motor was actually moving
in the engine bay even at idle. Replaced both
components and problem solved.

CAN YO TELL ME JUST BOUT HOW MUCH DID IT COST TO
GET THAT FIXED CAUSE I AM HAVING THE SAME PROBLEM
WITH MY '07 IMPALA AT FIRST WE THOUGHT IT NEEDED A
TUNE UP SO WE GOT THAT AND GOT THE SPARK PLUGS
CHANGED AND EVERYTHING, THEN THEY SAID IT WAS THE
FUEL INJECTORS SO WE GOT THAT FIXED AND IT WAS
STILL SPUTTERING AND JERKING THEN THEY SAID THE
VACUUM HOSE HAD A HOLE IN IT AT THIS POINT I HAVE
BEEN FRUSTRATED WITH THIS CAR SO I GOT THAT
CHECKED AND THEY SAID IT WAS THE FUEL INJECTORS
AGAIN BUT I KNEW IT WASN'T BECAUSE THE FUEL
INJECTORS ARE BRAND NEW WHAT COULD IT BE
HELP!!!!!!!!!

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